Locking mechanism for egg cartons

ABSTRACT

A locking mechanism for an egg carton having an integrally hinged tray and cover. The locking mechanism includes a plurality of locking flanges that extend forwardly from the bottom longitudinal edge of the cover&#39;&#39;s front wall and that fit into a plurality of rearwardly opening locking fingers on the top of the tray&#39;&#39;s front wall when the carton is closed. To prevent inadvertent opening of the carton, the fingers form part of a locking flap that is hingedly connected to the tray&#39;&#39;s front wall and that folds into the interior of the tray, where the packaged eggs hold the flap and its attached fingers in proper locking position.

I United States Patent n 13,552,635

[ 72] Inventors Theodore P. Martens 6} References Cited Pittsburgh; UNITED STATES PATENTS James Pam", Pillsburth, 3,100,593 8/1963 Alsman 229/25 1 pp 827,240 3,506,182 4/1970 Snow m1. 229/44 [22] Filed May 23,1969 l 451 Patented Jam 5, 1971 Primary Exammer-Leonard Summer [73] Assignee sinclaihKoppers Company Attorneys-Finnegan, Henderson and Farabow and Olin E.

Pittsburgh, Pa. wln'ams a partnership of Delaware ABSTRACT: A locking mechanism for an egg carton having an integrally hinged tray and cover. The locking mechanism includes a plurality of locking flanges that extend forwardly [54] EE E g FOR EGG CARTONS from the bottom longitudinal edge of the cover's front wall w 8 and that fit into a plurality of rearwardly opening locking fin- [52] U.S.Cl. 229/44, gers on the top of the tray's front wall when the carton is 229/2.5, 229/45 closed. To prevent inadvertent opening of the carton, the tin- [51] int. Cl 865d 85/32, gers form part of a locking flap that is hingedly connected to B65d l/24 the tray's front wall and that folds into the interior of the tray, [50] Field of Search ..229/2.5, 44, where the packaged eggs hold the flap and its attached fingers in proper locking position.

PATENTEDJAH 51971 3,552,635

sum 17 UF4 I gmeyamjnawson BZMW 'ITORNEYS PATENTEUJAN 5197: 35521635 SHEET 2 0F 4 INVENTORS THEODORE P. MARTENS JAMES R. PATTON jl fllzegan, dawn (K13520600- ATTORNEYS PATENIEU JAN 51911 FIG: 3

THEODORE P. MARTENS JAMES R. PATTON ATTORNEYf PATENIEU m 519?! 35521635 saw u 0F 4 INVENTORS THEODORE P. MARTENS JAMES R PATTON frmegan, J ndmrson 6w ATTORNEY 5 LOCKING MECHANISM FOR Eco CARTONS SPECIFICATION This invention relates to improvements in locking mechanisms for molded egg cartons.

Molded canons with various types of integrally molded locking mechanisms have been provided in the past for the packaging of eggs. One type of latch arrangement includes mating rib and channel elements along the front longitudinal edges of an egg carton that snap into and out of engagement to releasably hold the carton closed. Conventionally, the top rim of the front wall of the cartons tray curves upwardly and inwardly to form a latch channel, and the bottom rim of the front wall of the cartons cover projects outwardly to form a mateable rib. The rib snaps into the channel when the carton is closed where it is releasably held by the resilience of the cartons structure. I. I

A disadvantage of this type of latch arrangement, however, is the tendency of the rim forming channel to be pushed outwardly when top to bottom compressive forces are encountered during normal handling, thus allowing the carton to open unexpectedly or interfere with the packaging ofa plurali ty of loaded cartons in a larger container.

Attempts to improve the latch arrangement have included the application of an adhesive material between the channel and rib elements to strengthen their interlocking engagement. The requirement of an adhesive application step, however, necessarily adds to the time and expense of an automatic egg packaging operation in addition to making the carton inconvenient to open by the housewife.

In accordance with the present invention, a new and improved locking mechanism for an egg carton is provided in which the carton has hingedly connected bottom and cover sections that can assume a closed superimposed position with respect to each other, and a plurality of rows of egg accommodating cells in the bottom section of the carton.

The locking mechanism includes a locking flap hingedly connected to the top of the bottom sections front wall that is folded into overlapped relation with the inside of bottom sections front wall and held in folded position by the eggs packaged in the forward row of egg accommodating cells; a plurality of rearwardly opening locking fingers integral with the locking flap and having an upper locking edge, said fingers projecting upwardly from the top-of the bottom sections front wall when the flap is in folded position; and a plurality of spaced locking flanges projecting forwardly from the bottom longitudinal edge of the cover sections front wall, the locking flanges fitting into the locking fingers and engaging the underside of the fingers upper locking edges when the carton is closed to hold the sections together.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory but are not restrictive of the invention.

The accompanying drawings which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and together with the description serve to explain the principles of the invention.

Of the drawings:

FIG. I is a perspective view of an open egg carton embodying the locking mechanism of this invention;

FIG. 2 is a top plan view of the egg carton of FIG. I in an open position;

FIG. 3 is an enlarged sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is an enlarged sectional view taken along the line 4-4 of FIG. 2; i

FIG. 5 is an enlarged fragmentary sectional view similar to FIG. 4 and showing a packaged egg holding the locking flap in folded position; and

FIG. 6 is a fragmentary perspectiveview of the carton of FIG. 1 in a closed position. 7

Reference will now be made in detail to the present preferred embodiment of this invention, an example of which is illustrated in the accompanying drawings.

The carton illustrated in the drawings and contemplated for use with the locking mechanism of this invention is an egg carton having a cover section or lid 10 and a bottom section or tray 12. The cover and bottom sections rear walls 14 and I6, respectively, are hingedly connected by an integral web I8. Bottom section 12 has a plurality of egg accommodating cells 20 arranged in parallel rows. While the number and rows of cells may vary, the bottom section preferably consists of a dozen cells arranged in two (2 parallel rows of six (6 cells each.

A wide variety of materials may be used in the manufacture of the egg carton structure illustrated in, the drawings. Molded paper pulp, pasteboard, plastic, and the like, for example, may be used. A preferred material, however, is thermoplastic foam, such as, for example, foam polystyrene or other polymers, such as polyethylene, polypropylene, polyvinylchloride, and the like. Preferably, and as shown in the drawings, the egg carton and locking mechanism are of unitary molded construction produced by vacuum molding or match molding techniques from a sheet of polystyrene foam.

Conventionally, the carton includes an outwardly and laterally extending flange 22 that extends around the bottom of the cover sections rear, side, and front walls and a corresponding lateral flange 24 that extends around the top of the bottom sections rear, side, and front walls. The flanges 22 and 24 are in substantial flush load-bearing engagement when the carton is closed to provide support against crushing of the carton when loaded cartons are arranged in stacked relation.

In accordance with the invention, interlocking means are provided on the front walls of the cover and bottom sections for releasably holding the carton closed. As embodied, and as shown in the drawings, the interlocking means includes a locking flap 26-hingedly connected at 28 to the forward edge 29 of the bottom sections lateral flange 24. As best shown in FIGS. 1 and 6, locking flap 26 is folded into overlapped relation with the top of flange 24 to place the flap in locking position.

In accordance with the invention, locking flap 26 includes a plurality of depending tabs 30 that extend into the interior of the forward row of egg accommodating cells 20 when the flap is folded into locking position. As best-shown in FIG. 5, each tab 30 fits into a corresponding recess 3:2 on the inside surface 34 of the bottom sections front wall'35 and is of sufficient length so that it is engaged by an egg 37 packaged in the forward row of cells 20 to hold locking flap 26 in its folded and locking position.

The interlocking means further includes a plurality of rear wardly opening locking fingers 36 integral with locking flap 26 that project upwardly from the top ofthe bottom sections lateral flange 24 when the flap is in folded position. As best shown in FIG. 3, each locking finger.36 includes an upper locking edge 38 and depending sidewalls 40 connecting the locking edge to flap 26 and defining a rearwardly opening recess 42.

Further, and as best shown in FIG. 1, a plurality of spaced locking flanges 44 corresponding to locking fingers 36 project forwardly from the bottom longitudinal edge of the cover sections front wall 46. In closed position, and as shown in FIG. 6, locking flanges 44 fit into the recesses 42 in locking fingers 36 and engage the underside of the fingers top edges 38 to hold the cover and bottom sections together.

To provide clearance for locking fingers 36 when the carton is in closed position, the cover sections front wall 46 has a plurality of pairs of angularly offset vertical walls 48. The walls of each pair intersect one another behind each locking flange 44 to form a channel 50 that extends vertically up from the flange. Thus when the carton is locked shut, and as best shown in FIG. 6, fingers 36 extend into channels 50 so that the flanges 44 can fit into and engage the underside of the fingers locking edges.

Preferably, locking flanges 44 are coplanar with and separated by lateral flangesegments 52 that form a part of the cover sections lateral flange 22. The flange segments 52 and locking flanges 44 are raised abovethe flange 22 along the front of the carton a distance sufficient to provide clearance for folded flap 26, so that flange segments 52 he in substantial flush load-hearing engagement with the top of the flap when the carton is closed.

During packaging, the eggs being inserted into cells 20 depress tabs 30 of locking flap 26 into recesses 32 to hold flap 26 in its folded and locking position. Thereafter, and to lock the carton shut, cover section is rotated about hinge 18 toward closing relationship with bottom. section 12, and the front wall 46 of cover section 10 is pressed inwardly in the direction of arrows 54 (see FIG. 6) to permit locking flanges 44 to pass behind the rearward edge of locking fingers 36. After closure, pressure on the cover sections front wall 46 is released, allowing locking flanges 44 to snap forward into recesses 42 under the resilience of the cartons structure, and engage the underside of the fingers locking edges 38.

To open the carton, the front wall 46 of cover section It) is pressed inwardly to push locking flanges 44 out of locking fingers 36 and the cover is pulled upwardly.

As best shown in FIGS. 3 and 4, integral web 18, hingedly connecting the cover and bottom sections, is preferably doubly creased at 60 and 62 with a compressible midportion 64 to resiliently urge the cover and bottom sections apart. Thus, locking flanges 44 tightly engage the underside of the top edge 38 of locking fingers 36 when the carton is closed for more positive locking.

The invention thus provides a new and improved locking mechanism for molded egg cartons that facilitates easy closing on automatic egg packaging machines and that provides more positive locking by utilizing packaged eggs to hold the mechanism in locked position to prevent inadvertent opening of the carton during handling, shipping, or storage. Further, the locking mechanism of this invention can be integrally molded with the basic structure of the egg' carton from a sheet of suitable material, using conventional molded techniques.

The invention in its broader aspects is not limited to the specific details shown and described,.and departures may be made from such details without departing from the principles of the invention and without sacrificing its chief advantages.

We claim:

1. An egg carton comprising a bottom section having a front wall, a rear wall, and a plurality of rows of egg accommodating cells; a cover section having a front wall and a rear wall, the cover and bottom sections rear walls being hingedly connected so that the cover section can assume a closed superimposed position with respect to the bottom section; and interlocking means along the front walls of the cover and bottom sections for releasably holding the canon closed, said interlocking means comprising:

a. a locking flap hingedly connected to the top of the bottom sections front wall and folded into overlapped relation with the inside of the bottom scctions front wall. said flap being held in folded position by eggs packaged in the forward row of egg accommodating cells;

. a plurality of rearwardly opening locking lingers integral with the locking flap and having an upper locking edge, said fingers projecting upwardly from the top of the bottom sections front wall when the flap is in folded positionjand c. a plurality of correspondingly spaced locking flanges projecting forwardly from the bottom longitudinal edge of the cover sections front wall,-the locking flanges fitting into the locking fingers and engaging the underside of the lingers upper locking edge when the carton is closed to hold the sections together.

2. The carton of claim 1, wherein the carton and intcrlocking means are ofunitary molded Construction.

3. The carton of claim 2, wherein the carton and interlocking means are formed of molded polystyrene foam.

4. The carton of claim 1, including a laterally extending flange along the top of the bottom sections front wall, in

which the locking flap is hinged to the forward edge of the lateral flange so that it overlies the top of a portion of the flange when m folded position and m which the locking flap includes a plurality of depending tabs that extend into the interior ofa plurality of egg cells, said tabs being engaged by the eggs packaged in said cells to hold the flap in folded position.

5. The carton of claim 4, including a laterally extending flange along the bottom of the cover sections front wall lying in substantial flush engagement with the bottom section's flange when the carton is closed, the portion of said covers flange adjacent the locking flap being raised so that is lies flush with the top of the folded flap when the sections are in closed position.

6. The carton of claim 5, wherein the locking flanges on the cover section are coplanar with and interrupt the raised portion of the cover sections lateral flange adjacent the locking 

1. An egg carton comprising a bottom section having a front wall, a rear wall, and a plurality of rows of egg accommodating cells; a cover section having a front wall and a rear wall, the cover and bottom sections'' rear walls being hingedly connected so that the cover section can assume a closeD superimposed position with respect to the bottom section; and interlocking means along the front walls of the cover and bottom sections for releasably holding the carton closed, said interlocking means comprising: a. a locking flap hingedly connected to the top of the bottom section''s front wall and folded into overlapped relation with the inside of the bottom section''s front wall, said flap being held in folded position by eggs packaged in the forward row of egg accommodating cells; b. a plurality of rearwardly opening locking fingers integral with the locking flap and having an upper locking edge, said fingers projecting upwardly from the top of the bottom section''s front wall when the flap is in folded position; and c. a plurality of correspondingly spaced locking flanges projecting forwardly from the bottom longitudinal edge of the cover section''s front wall, the locking flanges fitting into the locking fingers and engaging the underside of the fingers'' upper locking edge when the carton is closed to hold the sections together.
 2. The carton of claim 1, wherein the carton and interlocking means are of unitary molded construction.
 3. The carton of claim 2, wherein the carton and interlocking means are formed of molded polystyrene foam.
 4. The carton of claim 1, including a laterally extending flange along the top of the bottom section''s front wall, in which the locking flap is hinged to the forward edge of the lateral flange so that it overlies the top of a portion of the flange when in folded position and in which the locking flap includes a plurality of depending tabs that extend into the interior of a plurality of egg cells, said tabs being engaged by the eggs packaged in said cells to hold the flap in folded position.
 5. The carton of claim 4, including a laterally extending flange along the bottom of the cover section''s front wall lying in substantial flush engagement with the bottom section''s flange when the carton is closed, the portion of said cover''s flange adjacent the locking flap being raised so that is lies flush with the top of the folded flap when the sections are in closed position.
 6. The carton of claim 5, wherein the locking flanges on the cover section are coplanar with and interrupt the raised portion of the cover section''s lateral flange adjacent the locking fingers.
 7. The carton of claim 1, wherein the hinged connection between the cover and bottom sections'' rear walls resiliently urges the sections apart so that the locking flanges tightly engage the underside of the locking fingers'' upper locking edges when the sections are in closed position. 